Sato Pharmaceutical Co., Ltd. and Eisai Co., Ltd. have announced significant changes to their partnership regarding the oral antifungal medication NAILIN® Capsules 100mg (fosravuconazole). The current co-promotion agreement will conclude on March 31, 2025, with Sato Pharmaceutical assuming full promotional responsibilities after a planned transition period.
Under the new agreement, Eisai will continue promotional activities during a one-year transition period from April 1, 2025, to March 31, 2026. Following this period, Sato Pharmaceutical will independently manage all promotional operations for the antifungal agent. The arrangement includes a lump sum payment from Sato Pharmaceutical to Eisai.
Product Background and Development
NAILIN® Capsules 100mg, marketed in Japan since July 2018, contains fosravuconazole, an innovative oral antifungal compound developed by Eisai. The drug represents a significant advancement in antifungal therapy, utilizing a prodrug formulation that enhances the solubility and bioavailability of its active component, ravuconazole.
The medication's mechanism of action centers on inhibiting ergosterol biosynthesis, a crucial component of fungal cell membranes. This targeted approach has proven effective in treating various fungal infections, particularly onychomycosis, for which it received approval in January 2018.
Strategic Partnership Evolution
The relationship between Sato Pharmaceutical and Eisai has evolved beyond their initial co-promotion agreement. In July 2024, the companies entered into a broader licensing agreement, granting Sato Pharmaceutical development and commercialization rights across Asia and Oceania. This expanded territory includes ten ASEAN member states, Australia, New Zealand, South Korea, and Taiwan.
The development journey of fosravuconazole in Japan involved collaboration with Seren Pharmaceuticals Inc., which initially received exclusive development and commercialization rights from Eisai. This partnership led to successful clinical development and subsequent approval for onychomycosis treatment.
This strategic restructuring reflects both companies' commitment to ensuring continued market presence and growth for NAILIN® while optimizing their respective operational strengths in the pharmaceutical market.
